1. Field of the Invention
The present invention relates to rotary internal combustion engines and associated valve apparatus for inducting combustible mixture and educting exhaust gasses. More specifically, the present invention relates to a rotary cam internal combustion engine wherein reciprocating motion of horizontally opposed pistons is transformed into rotary output motion. Tubular rotary valves are employed for communication of combustible mixture to the cylinder bores and for extraction of exhaust gasses at appropriate times in the operational cycle of the engine.
2. Description of Prior Art
A number of rotary type internal combustion engines have previously been proposed with numerous objectives and advantages attibutable to each. However, of paramount importance today in the face of dwindling hydrocarbon fuel resources, is the search for a more fuel efficient internal combustion engine. In addition, improved engines which reduce or minimize pollutants discharged to the environment are highly desirable.
In response to these and other considerations, several rotary engines have been divised. For example, U.S. Pat. No. 3,964,450 to Lockshaw discloses a rotary cam type internal combustion engine comprising a stationary cylinder block and a rotatable casing. Reciprocating pistons are connected to a cam slot machined into the rotatable casing by means of a connecting rod having a cam follower secured to the outer end of the rod. The main drive shaft is attached to the rotatable casing and incorporates fuel intake and exhaust passages. A portion of the main drive shaft passes through the center of the stationary block and includes intake and exhaust ports which communicate in timed sequence with a single port opening in each of a plurality of radially oriented cylinder bores. In U.S. Pat. No. 2,894,496 to Townsend, a rotary internal combustion engine comprises a stationary outer cam apparatus, a rotary cylinder block assembly, and a stationary shaft which passes through the center of the cylinder block. The stationary shaft serves as an inlet and exhaust manifold for radially oriented cylinders, as well as a journal for the rotating block. Individual pistons within each radial cylinder include a cam follower means for imparting motion to the piston as the stationary cam surface is traversed. U.S. Pat. No. 4,038,953, also issued to Townsend, discloses a similar rotating block and stationary cam engine. However, improved means for accomplishing intake and exhaust functions are disclosed.
Although a number of rotary type combustion engines have been proposed, implementation of the concepts involved have been largely unsuccessful due to various factors such as complex mechanical arrangements, and exposure of rotating elements to the high temperatures of the exhaust gasses. For example, the engine disclosed in the Lockshaw patent requires a cam slot which restrains a cam follower in two directions to provide accurate positioning of the piston throughout the operational cycle. In both the Lockshaw and Townsend patents, rotating seals for intake and exhaust gasses are required due to clearances which must be provided between rotating and stationary components. Maintaining effective sealing of hot exhaust gasses for an acceptable period of time in these designs presents a major problem. Further, in the rotating block, stationary cam disclosures, the lack of positive means for stroking a piston through the intake cycle precludes practical application of this apparatus for a normally aspirated four cycle engine.